Nutritional therapy, that leads to the preservation and restoration of the body cell mass has significantly improved the morbidity and mortality of trauma, burns and sepsis. Parenteral nutrition has relied on central venous vein catheterization and the delivery of hyperosmolar solutions of protein components and glucose. This therapy ITPN) requies careful technique, supervision and monitoring. It is associated with considerable expense, risk and complications. The objctive of this investigation is to evaluate the protein sparing therapy using peripheral vein infusion of near isotonic amino acids solutions free of glucose. This concet is based on the ability of fat mobilization and kktosis to meet the greatest part of the body's energy requirements as in prlonged starvation. Thus the infused amino acids need not be expanded for energy production and remain available to replenish intracellular amino acid pools spplying prtein synthesis. The result is better nitrogen balance and preservation of the body cell mass. In addition when compared to similr patients receiving dextrose and water, preliminary evaluation of cellular immunity, suggests decreased impairment when patients are supported by the amino acid infusates. The branched chained amino acid metabolism is of key importance. It provides for the production of non-essential amino acids (NEAA) via transamination together with important gluconeogenic precursors, alanine and glutaaic acid via the BAA-Ala-glucose cycle and the BAA-Gln-NH3 cycle. While the carbon chain of the branched chained amino acid is providing energy to the muscle cell, the amine (-NH3) group is available for transamination or de novo synthesis of alanine. The BAA-Gln-NH3 cycle has not been appreciated since glutamine (Gln) is transported in the erythrocyte and not detected in plasma assays. Also, the ammonia is not produced until the glutamine is metabolized in the splanchnic tissue to glutamic acid and ammonia. This also provides an explanation why ammonia is produced in sterile animals and why attempts to control hepatic encephalophathy by sterilizing the gut or colon bypass surgery is not effective in many cases. The success of our initial studies in our 50 patients, utlizing this new therapy, warrants expanded clinical trals in order to establish a therapy that is effective, simple and safe.